Why Blitzboom? I did a similar calculation when I discovered Bitcoins, but never said anything about how valuable Bitcoins will be because I wanted to get mine while the price was low. It still is, but buying them at $.06 and $.30 was fantastic. I may buy more, but I'm waiting to see things unfold. The other reason is because I want BTC to have plenty of time to strengthen before governments attempt to stop it assuming they haven't gone bankrupt yet and assuming they will even have to power to do so. Egypt's government would have certainly made it difficult for Egyptians to use their BTCs AFAIK.
In response to the criticism of Blitz's original claim I will support his argument. There is a finite amount of purchasing power that exists. If infinite purchasing power existed it would have no meaning. We can't directly measure quantities of purchasing power because it is an idea, but mediums of exchange offer a method of approximating this purchasing power.
Obvious evidence (besides the logical necessity) exists in the fact that when the U.S. gov't increases the quantity of dollars in existence it waters down the value of dollars. This is because the sum of all dollars (both paper and electronic) represents a fixed quantity of purchasing power (how this amount was achieved is not relevant to my point). To alter the number of dollars only changes the purchasing power per dollar. To argue otherwise would be to suggest any government could create purchasing power by printing money, but this would create a situation of infinite purchasing power which negates the idea entirely.
The total amount of purchasing power in the world has been divided and allocated over all human history, across all assets, and in light of all economic events to arrive at the current situation of prices. Fiat currency systems have a certain amount of this purchasing power. If an individual sells 10k U.S. dollars today and buys 10k U.S. dollars worth of BTC at the same time then approximately 10k U.S. dollars worth of today's dollar purchasing power moved into BTC and the total purchasing power of the BTN will have gone up by the purchasing power equivalent to 10k U.S. dollars at today's valuation. The total monetary base of U.S. dollars is ~$2.2 trillion (
http://research.stlouisfed.org/fred2/series/BASE). If all the purchasing power represented by this quantity of money were transferred into 21 million BTCs (and from no source other than this) we would have a BTC value of 2.2x10^12 / 21x10^6 = $104,762 per BTC at today's valuation of the purchasing power of the U.S. dollar (minus a small amount that would occur due to the point at which the value of the dollar equals the value of it as a piece of paper). It is up to each individual to decide to what extent BTCs will replace or fail to replace other media of exchange to determine his/her appraisal of the final purchasing power of the BTN and individual BTCs. (Also note that credit contraction would shrink the monetary base if it occurs and government interference in the market would also change the price to some uncertain degree).